The present invention generally relates to apparatus and methods for the treatment of airstreams in an environmental control system (ECS) and, more particularly, to remove humidity from airstreams using an integrated heat exchanger system having a water extraction device.
In an aircraft environmental control system, humidity must be removed from the air prior to delivery to the pressurized cabin or equipment/electronics. The humidity can be removed by cooling the air below the water saturation temperature in reheater and condenser heat exchangers thus condensing most of the water vapor in the air into droplets. The droplets must then be separated from the air before the air is recuperatively heated in the reheater, and expanded and cooled in the cooling turbine.
Past high pressure water extraction loop designs include a condenser, a reheater, and a water extractor. However, the designs can be large, heavy, have many parts and components, and typically provide an installation challenge in many ECS applications. It is difficult to package the length required for current water extractor designs. The following are some examples.
U.S. Pat. No. 6,981,388 describes an overall water separation system that includes a reheater, condenser, and water separator. The patent also describes two sets of heat exchangers and water extractors. The airflow of each set goes through a reheater, condenser, water extractor and reheater.
U.S. Pat. No. 6,381,969 describes a two-spool environmental control system with two separator water extractors. One water extractor is downstream of the condenser and upstream of the high pressure turbine. The other water extractor is downstream of the high pressure turbine and before the reheater.
U.S. Pat. No. 5,887,445 describes a two-spool system that uses a standard high pressure water separation assembly. There are no details with respect to the water extractor function. Only one water removal device is used in this patent.
U.S. Pat. No. 6,128,909 describes an ECS with two-stage compression and the use of a subcooler between the first turbine and the second turbine. The patent describes water removal but does not describe how it is done.
U.S. Pat. No. 4,187,090 describes specific features in a regenerative heat exchanger pan (i.e., hot air outlet header) that guides the airflow, captures water droplets, collects water droplets, and drains water droplets through a drain tube. The patent describes a single baffle and scupper, and the scupper can have holes or slots. The patent describes a single staged device.
U.S. Pat. No. 3,849,095 describes a baffle/scupper geometry that can be used in a gas/liquid separator. The patent is specific with respect to baffle and scupper geometry where the crest of one baffle reaches toward the trough of the confronting baffle.
U.S. Pat. No. 8,444,732 describes a device for removing solid and liquid particles from a gaseous stream. It describes the use of identical modular components. The geometry includes pockets within the vane device to capture solids and liquids. The patent is specific with respect to vane geometry.
“Zero-G Water Selection Separator: A Performance Tradeoff” by R. Smith describes a zero-gravity application using finned surfaces coated with a cellular material that “wicks” the water away from the airstream.
“Dehumidification and Reheat in One Coil” by J. Siegel describes a low pressure device using refrigeration and heat coils to cool and condense entrained moisture in the air and then reheat.
As can be seen, there is a need for an improved heat exchanger system that includes water extraction.